1. Field of the Invention
The present invention relates to a communication terminal capable of using services of a service provider even if a look-up service cannot be searched, while consumption of resources is suppressed.
2. Related Background Art
Systems have recently been developed in which various apparatuses can be used together simply by connecting them to a network. In one system, a client as a communication terminal is connected to a service provider and a look-up server via a network, and can use services provided by the service provider.
In this system, the service provider provides its own functions (services). The look-up server registers services to be provided by the service provider, and provides the registered services to the client. When the service provider is connected to the network, it searches a look-up service in the network, and if the look-up service is found, it registers an agent object and attribute information of the service provided by the service provider in the look-up service. A look-up service of the look-up server has a function of storing an agent object which is program codes used by the client for using the service and the attribute information of the service, and provides the client with the registered service by supplying the agent object to the client.
The client intending to use service searches a look-up service in the network to check if a service to be used is registered in the look-up service. If there is the service to be used, the client acquires the agent object of the service from the look-up service, and communicates with the service provider with involvement of the agent object to thereby use the desired service. Such a system includes Jini™ and the like.
Consider, for example, the case that a portable communication terminal transmits data to a printer of a service provider to print it out. In this case, the portable communication terminal corresponds to a client, the printer corresponds to a service provider, and a service provided by the service provider corresponds to a printing service. The portable communication terminal acquires an agent object of a print service from a look-up server to thereby transmit print data to the printer and print it out.
With this system, however, the client cannot use service provided by the service provider if a look-up server providing a look-up service does not exist in the system or if existence of the look-up server providing look-up service cannot be confirmed because of a network failure or the like. Even if a service desired by a client exists on the network, this service cannot be used if the client cannot find the look-up service.
If the look-up service is newly activated on the client or service provider, the service can be used. However, in this case, resources of the apparatuses are consumed considerably.